Insight into the dicrotic notch in photoplethysmographic pulses from the finger tip of young adults

This study aims to investigate arterial stiffness in selected young adults by non-invasively determining the characteristics of the photoplethysmographic dicrotic notch. A total of 15 volunteers participated in this study, divided into four groups by age and gender. Contour analysis was applied to analyse the photoplethysmographic dicrotic notch, including time-related and height-related parameters. The height of reflected wave, mirrored by the notch relative amplitude (NRA), was found to be significantly larger in the older group compared to the younger group (p = 0.016). The timing of the reflected wave, measured by three parameters, i.e. notch index (NI), notch latency (NL) and peak-to-notch latency (PTNL), significantly increased in the female group compared to the male group (all p < 0.02). The results confirm that arterial stiffness occurs in young adults, and demonstrate that a difference of arterial stiffness exists between young male and female. This study indicates that examining the characteristic notch of the PPG pulse could help in identifying differences of vascular activities.

Bronchogenic and Esophageal Cyst With Laryngeal Malformations in a Thoroughbred Foal

This report documents an unusual case of congenital foregut cyst with dysphagia and stridor in a Thoroughbred foal. Histologically, the bilocular cyst, near the junction of larynx and trachea, had an epithelial lining of bronchogenic and esophageal origin. Concomitant malformation of the laryngeal muscles and cartilage resulted in a combination of anomalies that have not been reported in the human or veterinary literature.

Neutron scattering investigations of the partially ordered pyrochlore Tb(2)Sn(2)O(7)

Neutron scattering measurements have been performed on polycrystalline Tb(2)Sn(2)O(7) at temperatures above and below that of the phase transition, T(N) = 0.87 K, to investigate further the spin dynamics in the magnetically ordered state. In particular, new neutron spin echo results are presented showing a dependence on Q in the dynamics. We show evidence of the coexistence of static ferromagnetism and dynamically fluctuating spins down to 30 mK and we make a comparison of this partially ordered system to the spin liquid Tb(2)Ti(2)O(7).

Two-dimensional kagome correlations and field induced order in the ferromagnetic XY pyrochlore Yb2Ti2O7

Neutron scattering measurements show the ferromagnetic XY pyrochlore Yb2Ti2O7 to display strong quasi-two-dimensional (2D) spin correlations at low temperature, which give way to long range order (LRO) under the application of modest magnetic fields. Rods of scattering along 111 directions due to these 2D spin correlations imply a magnetic decomposition of the cubic pyrochlore system into decoupled kagome planes. A magnetic field of approximately 0.5 T applied along the [110] direction induces a transition to a 3D LRO state characterized by long-lived, dispersive spin waves. Our measurements map out a complex low temperature-field phase diagram for this exotic pyrochlore magnet.

Tunable (deltapi, deltapi)-type antiferromagnetic order in alpha-Fe(Te,Se) superconductors

The new alpha-Fe(Te,Se) superconductors share the common iron building block and ferminology with the LaFeAsO and BaFe(2)As(2) families of superconductors. In contrast with the predicted commensurate spin-density-wave order at the nesting wave vector (pi, 0), a completely different magnetic order with a composition tunable propagation vector (deltapi, deltapi) was determined for the parent compound Fe_{1+y}Te in this powder and single-crystal neutron diffraction study. The new antiferromagnetic order survives as a short-range one even in the highest T_{C} sample. An alternative to the prevailing nesting Fermi surface mechanism is required to understand the latest family of ferrous superconductors.

Itinerant spin excitations near the hidden order transition in URu(2)Si(2)

By means of neutron scattering we show that the high temperature precursor to the hidden order state of the heavy fermion superconductor URu(2)Si(2) exhibits heavily damped incommensurate paramagnons whose strong energy dispersion is very similar to that of the long-lived longitudinal f spin excitations that appear below T(0). This suggests that there is a strongly hybridized character to the itinerant excitations observed previously above the hidden order transition. Here we present evidence that the itinerant excitations, like those in chromium, are due to Fermi surface nesting of hole and electron pockets; hence the hidden order phase probably originates from a Fermi surface instability. We identify wavevectors that span nested regions of a f-d hybridized band calculation and that match the neutron spin crossover from incommensurate to commensurate on approach to the hidden order phase.

Inhibitions of vascular endothelial growth factor expression and foam cell formation by EGb 761, a special extract of Ginkgo biloba, in oxidatively modified low-density lipoprotein-induced human THP-1 monocytes cells

It has been reported that oxidatively modified low-density lipoprotein (Ox-LDL) involvement with vascular endothelial growth factor (VEGF) and foam cell formation play an important role in atherosclerosis (AS). Protective effects of Ginkgo biloba extract (EGb 761) have been identified for some cardiovascular and neurological disorders. The aim of this study was to investigate whether Ox-LDL regulates VEGF expression in human THP-1 monocytes, as well as the effect of EGb 761 on VEGF expression and the formation of foam cells. After exposure to Ox-LDL alone or in combination with EGb 761 for up to 48h, cell viability was measured using the MTT assay. VEGF protein content in the supernatant was analyzed by enzyme-linked immunosorbent assay (ELISA). VEGF mRNA was determined by real-time PCR. To determine the effect of EGb 761 on foam cell formation, an Ox-LDL-induced foam cell model was used. Ox-LDL inhibited the growth of THP-1 cells and EGb 761 increased the cell survival rate. Ox-LDL markedly increased VEGF expression in THP-1 cells in a time- and concentration-dependent manner, which was significantly suppressed by EGb 761. EGb 761 also inhibited monocyte/macrophage-derived foam cell formation. These results suggest that Ox-LDL is involved in the development of human AS through VEGF induction in monocytes, and that EGb 761 prevents in vitro atherogenesis, probably via downregulation of VEGF expression in monocytes and inhibition of monocyte/macrophage-derived foam cell formation. The findings suggest a mechanism for the in vivo anti-AS effect of EGb 761 and support its potential clinical use in AS.

Chemical pressure induced spin freezing phase transition in kagome pr langasites

The 2D kagome system Pr3Ga5SiO14 has been previously identified as a spin-liquid candidate in zero field, displaying no magnetic long-ranged order down to at least 35 mK. Perturbations upon such systems, either under applied fields or applied pressure, should induce a spin freezing phase transition, but there are very few experimental realizations of this phenomena other than the well-studied 3D pyrochlore Tb2Ti2O7. In this Letter, we report the observation of a spin freezing phase transition in Pr3Ga5SiO14 through the application of chemical pressure--that is, through a systematic substitution on the Si site with larger ions and an elongation of the nearest-neighbor Pr-Pr distance in the kagome lattice. This results in a suppression of the T2 component of the heat capacity, and the reduction of the exchange constant eventually leads to dipolar-driven spin freezing.

Assessment of self-reported and health-related quality of life in patients with brain tumours using a modified questionnaire

Assessment of quality of life (QoL) in patients who undergo surgery for brain tumours helps to guide surgery, reduce recurrence and minimize morbidity. This study validated a 25-item, modified QoL questionnaire based on the Medical Outcomes Survey SF-36 and the Karnofsky Performance Scale. The aims were for it to be brain tumour specific for Chinese patients, hence more sensitive, more acceptable, briefer and more easily used. A total of 431 patients with brain tumours were compared with 96 age-matched healthy controls. A surgery-related QoL curve was used to help identify a threshold satisfaction point for QoL. Physiological function, psychological function, satisfaction with medical care and self-care ability of the patients were compared pre-operatively and post-operatively. Cronbach's alpha-coefficient was 0.9521 and the correlation coefficient was 0.8685, suggesting good reliability and repeatability. With the exception of psychological function, which deteriorated, the modified QoL showed significant improvement in physiological function, satisfaction with medical care and self-care ability, and serves to stress the importance of post-operative psychological support.

Weakly coupled s=1/2 quantum spin singlets in Ba3Cr2O8

Using single crystal inelastic neutron scattering with and without the application of an external magnetic field and powder neutron diffraction, we have characterized magnetic interactions in Ba3Cr2O8. Even without a field, we found that there exist three singlet-to-triplet excitation modes in the (h, h, l) scattering plane. Our complete analysis shows that the three modes are due to spatially anisotropic interdimer interactions that are induced by lattice distortions of the tetrahedron of oxygens surrounding the Jahn-Teller active Cr5+(3d1). The strong intradimer coupling of J0=2.38(2) meV and weak interdimer interactions (|Jinter|< or =0.52(2) meV) makes Ba3Cr2O8 a good model system for weakly coupled s=1/2 quantum spin dimers.

Association study between adolescent idiopathic scoliosis and the DPP9 gene which is located in the candidate region identified by linkage analysis

BACKGROUND

It has been recognised that genetic or hereditary factors may contribute to the aetiology of adolescent idiopathic scoliosis (AIS). Recently, two linkage analyses have identified 19p13.3 as the candidate region for AIS. The dipeptidyl peptidase 9 (DPP9) gene is located on chromosome 19p13.3.

OBJECTIVE

To investigate whether DPP9 gene polymorphisms are associated with the occurrence or curve severity of AIS.

METHODS

571 girls with AIS and 236 normal controls were recruited. Using the Chinese data from the HapMap project, a set of tagging single-nucleotide polymorphisms (tagSNPs) were defined for the DPP9 gene. Five SNPs were genotyped by PCR restriction fragment length polymorphism. Statistical analysis of genotype frequencies between cases and controls was performed by the chi2 test. One-way analysis of variance was used to compare mean maximum Cobb angles with different genotypes in case-only analysis.

RESULTS

Genotype frequencies were comparable between cases and controls for all five polymorphisms (p>0.05). The mean maximum Cobb angles of different genotypes were similar to each other for all five polymorphisms.

CONCLUSIONS

The DPP9 gene is not associated with the occurrence or curve severity of AIS. It is neither a disease-predisposition nor a disease-modifying gene of AIS.

Neutron-diffraction measurements of magnetic order and a structural transition in the parent BaFe2As2 compound of FeAs-based high-temperature superconductors

The recent discovery of superconductivity in (Ba,K)Fe2As2, which crystallizes in the ThCr2Si2 (122) structure as compared with the LnFeAsO (Ln is lanthanide) systems that possess the ZrCuSiAs (1111) structure, demonstrates the exciting potential of the FeAs-based materials for high-T{C} superconductivity. Here we report neutron diffraction studies that show a tetragonal-to-orthorhombic distortion associated with the onset of q=(101) antiferromagnetic order in BaFe2As2, with a saturation moment 0.87(3)micro {B} per Fe that is orientated along the longer a axis of the ab planes. The simultaneous first-order structural and magnetic transition is in contrast with the separated transitions previously reported in the 1111-type materials. The orientational relation between magnetic alignment and lattice distortion supports a multiorbital nature for the magnetic order.

Crystal structure and antiferromagnetic order in NdFeAsO1-xFx (x=0.0 and 0.2) superconducting compounds from neutron diffraction measurements

The transition temperature T{C} approximately 26 K of the recently discovered superconductor LaFeAsO1-xFx is extremely sensitive to the lanthanide ion, reaching 55 K for the Sm containing oxypnictides. Therefore, it is important to determine how the moment on the lanthanide affects the overall magnetism in these systems. Here we report a neutron diffraction study of the Nd oxypnictides. Long-ranged antiferromagnetic order is apparent in NdFeAsO below 1.96 K. Rietveld refinement shows that both Fe and Nd magnetic ordering are required to describe the observed data with the staggered moment 1.55(4)micro{B}/Nd and 0.9(1)micro{B}/Fe at 0.3 K. The other structural properties such as the tetragonal-orthorhombic distortion are found to be very similar to those in LaFeAsO. Neither the magnetic ordering nor the structural distortion occur in the superconducting sample NdFeAsO0.80F0.20 at any temperatures down to 1.5 K.

Dynamic spin ice: Pr2Sn2O7

In this Letter, we report a new spin ice--Pr2Sn2O7--which appears to have enhanced residual entropy due to the dynamic nature of the spins. Neutron scattering experiments show that at 200 mK, there is a significant amount of magnetic diffuse scattering which can be fit to the dipolar spin-ice model. However, these short-ranged ordered spins have a quasielastic response that is atypical of the canonical spin ices, and suggests that the ground state is dynamic (i.e., composed of locally ordered two-in-two-out spin configurations that can tunnel between energetically equivalent orientations). We report this as an example of a dynamic spin ice down to 200 mK.

Crystalline electric field as a probe for long-range antiferromagnetic order and superconducting state of CeFeAsO(1-x)F(x)

We use inelastic neutron scattering to study the crystalline electric field (CEF) excitations of Ce3+ in CeFeAsO(1-x)F(x) (x=0, 0.16). For nonsuperconducting CeFeAsO, the Ce CEF levels have three magnetic doublets in the paramagnetic state, but these doublets split into six singlets when the Fe ions order antiferromagnetically. For superconducting CeFeAsO0.84F0.16 T(c)=41 K), where the static antiferromagnetic order is suppressed, the Ce CEF levels have three magnetic doublets at [formula: see text], 18.7, 58.4 meV at all temperatures. Careful measurements of the intrinsic linewidth Gamma and the peak position of the 18.7 meV mode reveal a clear anomaly at T(c), consistent with a strong enhancement of local magnetic susceptibility chi'' [formula: see text] below T(c). These results suggest that CEF excitations in the rare-earth oxypnictides can be used as a probe of spin dynamics in the nearby FeAs planes.

Spin waves and quantum criticality in the frustrated XY pyrochlore antiferromagnet Er2Ti2O7

We report detailed measurements of the low temperature magnetic phase diagram of Er2Ti2O7. Heat capacity and time-of-flight neutron scattering studies of single crystals reveal unconventional low-energy states. Er3+ magnetic ions reside on a pyrochlore lattice in Er2Ti2O7, where local XY anisotropy and antiferromagnetic interactions give rise to a unique frustrated system. In zero field, the ground state exhibits coexisting short and long-range order, accompanied by soft collective spin excitations previously believed to be absent. The application of finite magnetic fields tunes the ground state continuously through a landscape of noncollinear phases, divided by a zero temperature phase transition at micro{0}H{c} approximately 1.5 T. The characteristic energy scale for spin fluctuations is seen to vanish at the critical point, as expected for a second order quantum phase transition driven by quantum fluctuations.

External magnetic field effects on a distorted kagome antiferromagnet

We report bulk magnetization, and elastic and inelastic neutron scattering measurements under an external magnetic field H on the weakly coupled distorted kagome system, Cu2(OD)3Cl. Our results show that the ordered state below 6.7 K is a canted antiferromagnet and consists of large antiferromagnetic ac components and smaller ferromagnetic b components. By first-principles calculations and linear spin wave analysis, we present a simple spin Hamiltonian with nonuniform nearest neighbor exchange interactions resulting in a system of coupled spin trimers with a single-ion anisotropy that can qualitatively reproduce the spin dynamics of Cu2(OD)3Cl.

HPLC-UV method development and validation for the determination of low level formaldehyde in a drug substance

A reversed-phase high-performance liquid chromatographic method (HPLC) with diode-array detection is developed and validated for the quantitative determination of formaldehyde in a drug substance. Formaldehyde (HCHO) is reacted with 2,4-dinitrophenylhydrazine (DNPH) to form a Schiff base (HCHO-DNPH derivatization product), which has an absorbing maximum (lambda max) at 360 nm. The HPLC method employs a C8, 3-microm particle size analytical column (150 mm x 4.6 mm), 15-microL injection volume, column temperature controlled at 30 degrees C, detection at 360 nm, and a water-acetonitrile (55:45, v/v) mobile phase at a flow rate of 1 mL/min. These conditions resolve the HCHO-DNPH product from unreacted DNPH, the drug substance and related impurities, as well as diluent peaks within 20 min. The retention time of the HCHO-DNPH product is approximately 6.4 min. The method is linear, accurate in the specified range (0.33-333 ppm), and robust based on analyte (HCHO-DNPH derivatization product) stability in standard and sample. Detection limit is 0.03 ng (0.1 ppm).

In-gel digestion of proteins for MALDI-MS fingerprint mapping

Mass spectrometry (MS) has emerged as a sensitive, versatile, and rapid method for protein identification, following the advent of electrospray ionization mass spectrometry (ESI-MS) and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). The advantages of MALDI-MS over ESI-MS include its relatively high tolerance to contamination from biological matrices, its high sensitivity, the relative ease of interpreting spectra from mixtures, and the formation of singly protonated molecular ions for tandem analysis. Peptide fingerprint mass mapping and partial peptide sequencing using post-source decay and ladder sequencing by MALDI-MS in combination with algorithms for sequence database interrogation have the potential for identification and structural investigation of proteins. This unit describes in-gel digestion for peptide mass mapping of picomole to subpicomole quantities of protein derived from Coomassie- or silver-stained polyacrylamide gels. After digestion, the peptides are extracted from the gel and mass analyzed.

Frustrated spin correlations in diluted spin ice Ho(2-x)La(x)Ti(2)O(7)

We have studied the evolution of the structural properties as well as the static and dynamic spin correlations of spin ice Ho(2)Ti(2)O(7), where Ho was partially replaced by non-magnetic La. The crystal structure of diluted samples Ho(2-x)La(x)Ti(2)O(7) was characterized by x-ray and neutron diffraction and by Ho L(III)-edge and Ti K-edge extended x-ray absorption fine structure (EXAFS) measurements. It is found that the pyrochlore structure remains intact until about x = 0.3, but a systematic increase in local disorder with increasing La concentration is observed in the EXAFS data, especially from the Ti K edge. Quasi-elastic neutron scattering and ac susceptibility measurements show that, in x≤0.4 samples at temperatures above macroscopic freezing, the spin-spin correlations are short ranged and dynamic in nature. The main difference with pure spin ice in the dynamics is the appearance of a second, faster, relaxation process.